1. Field of the Invention
The invention is directed to a combination of a main carrier and a printed circuit board populated with electrical and electronic components and, more particularly, to such combinations as may be used in applications deployed in a mechanically demanding environment, such as in a vehicle.
2. Description of the Related Art
Combinations of main carriers and printed circuit boards are used in many kinds of electronic systems. If combinations of this type are used, for example, in vehicles with electrical main or auxiliary drives, the harshness of the environment demands that the combination be mechanically robust. Especially if structures of this type are populated with components having very different masses, meeting the demands for robustness with respect to vibrations is difficult according to commonly used prior art combinations.
Here and hereinafter “light” electrical or electronic components should be understood to mean by way of example: individual CMOS transistors, resistors that can be loaded with up to one watt and further components having a comparable mass. “Heavy” electrical or electronic components should be understood to mean components having at least a hundred times the mass of the light components. They are, by way of example capacitors, transformers or power semiconductor modules.
FIG. 5 illustrates a combination in accordance with the prior art. Here the illustration shows a printed circuit board 15 rigidly connected to a main carrier 35 by means of suitable connecting devices 205 such as screw connections guided in sleeves, by way of example. Main carrier 35 is embodied, for example, as a housing composed of die-cast aluminum, as is particularly suitable for the combination of different circuit combinations in vehicles. In this case, the housing has a significantly higher mass in comparison with the printed circuit board with the components 4, 142 that are arranged thereon and connected as appropriate for the requirements of the application. Main carrier 35, here the housing itself, is preferably connected directly and rigidly to the vehicle (not shown), by way of example.
As a result of the influence of vibrations that can occur with different amplitudes and frequencies both parallel and perpendicular to the plane of printed circuit board 15, primarily the fixings, generally soldered connections, of the heavy components 4 are loaded. A capacitor is illustrated here as an example of a heavy component, the capacitor being connected to printed circuit board 35, or the conductor tracks there, by means of a soldering connection. For more stable fixing, an additional adhesive-bonding connection between capacitor 4 and printed circuit board 15 is illustrated here and generally known.
Despite this additional adhesive-bonding connection, the fixing of the heavy component proves to be insufficient for vibrations that occur, for example in vehicles, wherein the vibrations damage the electrically conductive connection between the heavy component and the conductor tracks of the printed circuit board. This is caused by the fact that here the heavy connection partner is bonded to the light connection partner and the soldering connection is therefore subjected to correspondingly severe loading on account of the mass inertia.